The Olympic rings suspended from the walkways above Tower Bridge were celebrated in an evening light show last night.

The rings, measuring 25 metres wide, 11.5 metres tall and weighing three tonnes, were lifted into place two weeks ago, but were lowered into place yesterday to mark 30 days until the Games begin.

The lights, a permanent fixture sponsored by EDF energy, are in keeping with the sustainability theme of the Games and are made up of high-powered LEDs that use less electricity. The lighting will not need to be replaced for another 25 years.

Lord Coe said: "The Olympic rings are an iconic symbol, inspiring athletes and uniting people around the world. To athletes they represent the culmination of thousands of hours of training and reaching the highest level in sport."

"With one month to go to the Olympic Games Opening Ceremony, these spectacular rings on one of London's most famous landmarks will excite and inspire residents and visitors in the capital."

Tower Bridge is one of the most globally recognised landmarks and the sight of the rings hanging underneath will no-doubt form one of the more lasting images of the Games.

Interestingly, there is a Port of London Authority by-law which dictates that a bale of hay has to be hung from the bridge to warn approaching large ships when the clearance height of the bridge is restricted. Fortunately for those wanting a picture un-obscured by farmyard sundries, a bale of hay will not be needed this time as the rings will rotate upwards allowing ships with tall masts to pass underneath as normal.

The last time a bale of hay was suspended from the bridge was last year while bridge re-painting work was taking place.